1. Field of the Invention
The present invention relates to press wheel type seeders utilizing the press wheel to provide individual depth control for each of the furrow openers.
2. Prior Art
In the prior art various depth control means have been utilized for controlling the depth of furrow openers in planters and seeders.
An individual depth control is shown in U.S. Pat. No. 2,554,061 issued to Sandberg. In this particular device disc furrow openers are utilized and are mounted onto a support arm. A link has a press wheel at its rear end and is pivotally mounted to the same support arm at its leading end. A threaded adjustment is provided for regulating the relationship between the link and the support arm for the furrow opener. The adjustment provides control of the height relationship between the furrow opener and the press wheel. However the range of adjustment is limited, and the overhead clearance is also limited with the device shown in this patent because the link extends over the furrow opener.
U.S. Pat. No. 2,496,885 also shows a device having a covering wheel for a planter that is spring loaded for exerting pressure for covering seed. The device is used primarily for sugar beet planting and the covering wheel does not accurately control the depth of the furrow openers, but rather resiliently packs the ground around the planted seeds.
Another press wheel device is shown in U.S. Pat. No. 3,509,947.
U.S. Pat. No. 2,685,243 also shows a depth wheel for seed planters where the wheel is independently mounted on the frame and adjustable to control the depth of the planter.
In most grain drills several press wheels are mounted onto a common shaft or frame so that several press wheels move as a gang or unit. This tends to cause irregular packing, and also makes depth control difficult.